1. Field of the Invention
The present invention relates to a terminal and cell information management method thereof. In more particular, the present invention relates to a terminal and method of managing cell information on neighbor cells for Minimization of Drive Test (MDT) measurement report.
2. Description of the Related Art
Typically, the mobile communication system has been developed for the user to communicate on the move. With the rapid advance of technologies, the mobile communication system has evolved to the level capable of providing high speed data communication service as well as voice communication service. Recently, the 3GPP, as one of the next generation mobile communication standardization organizations, is in the progress of standardization of Long Term Evolution-Advanced (LTE-A). LTE-A is one of the high speed packet-based communication technologies supporting data rate higher than that of the current mobile communication technology.
With the evolvement of the 3GPP standard, many discussions are being conducted for optimizing the radio network in addition to the effort for increasing data rate. In the initial radio network configuration or optimization stage, a base station or a base station controller should collect radio environment information related to its own cell coverage, and this process is called Drive Test. Since the conventional drive test is performed in such a way that an operator carries the test apparatuses on a vehicle while performing the measurement task repeatedly for long time. The measurement result is used to configure the system parameters of the base stations or base station controllers. Such a conventional drive test increases total costs and time of the radio network optimization and maintenance.
Study on minimization of drive tests and enhancement of radio environment analysis process and manual configuration is being conducted in the name of MDT (Minimization of Drive Test). In more detail, the terminal measures the cell information and supplementary information on the neighbor eNBs. The terminal reports the radio channel measurement information to the eNB periodically or immediately in response to a specific event or after a predetermined time has elapsed from the time point when the radio channel measurement information has been logged. At this time, the UE operation of transmitting the measured cell information and other supplementary information to the UE is referred to as MDT measurement information report. If it is in the state capable of communicating with the eNB, the terminal transmits the neighbor cell information measurement result to the eNB immediately. Otherwise, if it is not in the state capable of communicating with the eNB, the terminal retains the logged measurement information and, when it becomes possible to communicate with the eNB, transmits the retained MDT measurement report. The eNB uses the MDT measurement information received from the UE for cell coverage optimization.